Wzrost, struktura i właściwości fizykochemiczne ultracienkich warstw tlenków żelaza oraz wanadu
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Date
2022
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Growth, structure and physicochemical properties of ultrathin iron and vanadium oxide films
Abstract
Ultracienkie warstwy tlenków metali wytworzone na monokrystalicznych podłożach metali szlachetnych wykazują unikatowe właściwości elektronowe, magnetyczne i katalityczne, związane głównie z ograniczonej wymiarowości oraz oddziaływaniem z podłożem. Celem niniejszej pracy było zbadanie wzrostu, struktury i właściwości fizykochemicznych ultracienkich wysp i warstw tlenków żelaza oraz wanadu (odpowiednio FeOx i VOx) na wybranych podłożach monokrystalicznych. Badania były realizowane w warunkach UHV z wykorzystaniem metod STM, STS, LEED i XPS. Eksperymenty przeprowadzone dla układu FeO/Ru(0001) pozwoliły na określenie struktury tlenku o grubości jednej i dwóch monowarstw, a także zmian strukturalnych zachodzących w dwuwarstwie wskutek ekspozycji na atomowy tlen i/lub CO. Warstwy FeO były też wytwarzane różnymi metodami na podłożu Ag(111). Zaobserwowano kilka struktur tlenków żelaza, w tym wcześnie nieopisaną w literaturze nadstrukturę Moiré. Wysoce-zorganizowane wyspy VOx wytworzono na Ru(0001). Pokazano, że tlenek ten jest pokryty periodycznie ułożonymi obiektami, które przypisano do grup V=O i które mogą być usuwane z powierzchni z wykorzystaniem desorpcji stymulowanej elektronami z ostrza mikroskopu STM. Praca poszerza obecny stan wiedzy na temat ultracienkich wysp i warstw tlenków metali przejściowych wytworzonych na monokrystalicznych podłożach metali szlachetnych.
Ultrathin metal oxide films grown on noble metal single-crystal supports exhibit unique electronic, magnetic and catalytic properties. These properties originate mainly from their low-dimensionality and the interaction with the underlying substrate. The aim of this work was to study the growth, structure and physicochemical properties of ultrathin iron and vanadium oxide (FeOx and VOx, respectively) islands and films on selected noble metal single-crystal supports. The studies were carried out under UHV conditions using STM, STS, LEED and XPS. The experiments performed for FeO/Ru(0001) allowed determining the detailed structure of mono- and bilayer FeO species, as well as structural changes occurring in the bilayer system upon exposure to atomic oxygen and/or CO. FeO films were also grown on Ag(111) using different preparation methods. Several iron oxide structures were observed, including islands exhibiting a previously unreported Moiré superstructure. Well-ordered VOx islands were grown on Ru(0001). The oxide was found to be covered with periodically arranged features that were assigned to V=O groups, which could be removed by electron-stimulated desorption with a tip of a STM. The work broadens the existing knowledge on the growth, structure and properties of ultrathin transition metal oxide islands and films on noble metal single-crystal substrates.
Ultrathin metal oxide films grown on noble metal single-crystal supports exhibit unique electronic, magnetic and catalytic properties. These properties originate mainly from their low-dimensionality and the interaction with the underlying substrate. The aim of this work was to study the growth, structure and physicochemical properties of ultrathin iron and vanadium oxide (FeOx and VOx, respectively) islands and films on selected noble metal single-crystal supports. The studies were carried out under UHV conditions using STM, STS, LEED and XPS. The experiments performed for FeO/Ru(0001) allowed determining the detailed structure of mono- and bilayer FeO species, as well as structural changes occurring in the bilayer system upon exposure to atomic oxygen and/or CO. FeO films were also grown on Ag(111) using different preparation methods. Several iron oxide structures were observed, including islands exhibiting a previously unreported Moiré superstructure. Well-ordered VOx islands were grown on Ru(0001). The oxide was found to be covered with periodically arranged features that were assigned to V=O groups, which could be removed by electron-stimulated desorption with a tip of a STM. The work broadens the existing knowledge on the growth, structure and properties of ultrathin transition metal oxide islands and films on noble metal single-crystal substrates.
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Wydział Fizyki
Sponsor
This work was financially supported by the Foundation for Polish Science through the First TEAM/2016-2/14 (POIR.04.04.00-00-28CE/16-00) project co-financed by the European Union under the European Regional Development Fund.
Keywords
tlenki żelaza, tlenki wanadu, ultracienkie warstwy, struktura, właściwości fizykochemiczne, iron oxides, vanadium oxides, ultrathin films, structure, physicochemical properties